I. Field of the Invention
The present invention is directed to an adjustable resistance resistor network from which circuit parts can be removed or disconnected in order to change the resistance value.
II. Description of the Prior Art
A resistor network of this type is disclosed in British Pat. No. 1,236,580. In this patent, resistance wires have been arranged in a given configuration on a substrate strip which can be rolled up, and the resistance value can be set as desired by interrupting connections between the resistance wires. This prior art resistor is intended to be used as a series or shunt resistor in electrical measuring instruments. In contrast, it is not usable at all in exacting electronic circuits, due to the fact that the resistor has a large size, while on the other hand the resistance values are small and the elastic substrate is unreliable.
In electronic circuits adjustable potentiometers are used for the purpose of trimming the circuits after assembly. Such potentiometers are most often of the slide contact type. Such trimmer potentiometers are not reliable enough in exacting electronic circuits and are susceptible to changes of their resistance value when the point of contact becomes oxidized.